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Abstract

Studies in middle-aged adults report higher levels of glycated hemoglobin are associated with increased risk of mortality in non-diabetic individuals. Few studies have sufficient data to assess this association in older adults. We analyzed data from the Third National Health and Nutrition Examination Survey (1988-1994), Continuous NHANES (1999-2004), and their linked mortality data (through December 2006) to determine the risk of mortality by levels of HbA1c in older adults with and without diabetes. All analyses are weighted to represent the US population and to account for the complex survey design. Cox proportional hazard models examining the relationship between HbA1c and mortality were adjusted for age, sex, race, education, body mass index, smoking status, HDL cholesterol and hypertension. At baseline, in 7,405 adults, age ≥65 with HbA1c data (42.9% men; 7.5% black; 2.4% Mexican; mean age 73.5 (0.13)), 22.8% had clinically diagnosed diabetes (defined as self-reported physician diagnosis of diabetes and/or use of insulin or hypoglycemic medications). Over a median follow-up of 7.8 years, 4,625 participants (41.9%; 68.1 per 1000 person-years) died due to cardiovascular disease (CVD; n=1520) or non-CVD (n=3105). Non-diabetic older adults with a HbA1c between 5.7-6.4% (defined as “at risk for diabetes” by the American Diabetes Association) had a significantly greater risk of all-cause (HR: 1.39; 95% CI: 1.03-1.89) and non-CVD (HR: 1.55; 95% CI: 1.13-2.13) mortality compared to those with HbA1c<5.0% (referent). In older diabetic adults, there was a graded increase in mortality risk with significant associations found between HbA1c and all-cause (HR: 1.90; 95% CI: 1.13-3.28) and CVD (HR: 2.67; 95% CI: 1.17-6.09) mortality, in analyses comparing participants with a HbA1c between 8.0-8.9% to those with HbA1c <6.5% (referent). These data from a large, nationally representative sample of older adults indicate that dysglycemia is associated with increased mortality risk in older adults with and without diabetes.